PCQA-658 Avoid direct OptionParser usage

`OptionParser` usages leads to deprecation warning which fails tests.
`get_default_settings` helper function is better

GitOrigin-RevId: 1b07de2f69776cf0774e73d021532cfbc3beccaf

python/helpers/docstring_formatter.py

@@ -33,7 +33,7 @@ def format_fragments(fragments_list):
 def format_rest(docstring):
     from docutils import nodes
     from docutils.core import publish_string
-    from docutils.frontend import OptionParser
+    from docutils.frontend import get_default_settings
     from docutils.nodes import Text, field_body, field_name, SkipNode
     from docutils.parsers.rst import directives
     from docutils.parsers.rst.directives.admonitions import BaseAdmonition
@@ -58,7 +58,7 @@ def format_rest(docstring):
         def __init__(self, document):
             # Copied from epydoc.markup.restructuredtext._EpydocHTMLTranslator
             if self.settings is None:
-                settings = OptionParser([HTMLWriter()]).get_default_values()
+                settings = get_default_settings(HTMLWriter())
                 self.__class__.settings = settings
             document.settings = self.settings